LTK5

[CTA791]

Definitely going to follow this one! Do you plan on keeping the DOD/AFM? I'm interested to see you get it together and how you like the 6 speed. Theoretically it should be the best of both worlds with an over 4 to 1 first and double overdrive but everyone that I have talked to in their factory 6 speed trucks doesn't like them... However this was also in 3/4 tons with the 6l90. Maybe the 6l80s behave different in some way?

What I'll probably do next, after I get the frame/under cab cleaned up and prepped, is get the motor roughed in and fired up. That will all be it's own YouTube video, show everyone the K5 has not been forgotten, and introduce the drivetrain swap. It's kind of a shame, the suspension and 1 ton swap video I did got a TON of hits and interest, but the truck has basically been sitting for 2 years since then. I need to get some fresh K5 content out there, so that will be the quickest/easiest thing to do.

For YouTube videos, you shoot for a certain length. You gotta keep the topics interesting. You gotta keep in mind that only a small percentage of your audience are guys like us on this forum, more technical folks that want to see all the dirty details. I like to show as much as I can, but sometimes you have to skip over things. That's why I started this build thread, I'll be putting as much info, pictures and progress on here as I can.

So I say all that to answer your question, yes I will do an AFM and VVT delete on the L83, but that will be part of another video. Some odds and ends need to be addressed before it's ready to rock, such as no PS pump on a Gen V motor, 2wd 6L80 needs a t-case, and a few others.

As far as the 6L80, they have a tune-able and adaptive TCM, tap shift-able, and they hold a good bit of power in stock form, 4.02:1 first, double overdrive. I'll be driving this truck on the street a good bit, so the double OD is a plus. Also the super deep 1st gear is going to be a huge advantage when it comes to getting a good crawl ratio AND keeping it fairly street-able since I won't have to have stupid low axle gearing.

 

[bablazer73]

Nice build so far!

 

[CriticalAction]

What I'll probably do next, after I get the frame/under cab cleaned up and prepped, is get the motor roughed in and fired up. That will all be it's own YouTube video, show everyone the K5 has not been forgotten, and introduce the drivetrain swap. It's kind of a shame, the suspension and 1 ton swap video I did got a TON of hits and interest, but the truck has basically been sitting for 2 years since then. I need to get some fresh K5 content out there, so that will be the quickest/easiest thing to do.

For YouTube videos, you shoot for a certain length. You gotta keep the topics interesting. You gotta keep in mind that only a small percentage of your audience are guys like us on this forum, more technical folks that want to see all the dirty details. I like to show as much as I can, but sometimes you have to skip over things. That's why I started this build thread, I'll be putting as much info, pictures and progress on here as I can.

So I say all that to answer your question, yes I will do an AFM and VVT delete on the L83, but that will be part of another video. Some odds and ends need to be addressed before it's ready to rock, such as no PS pump on a Gen V motor, 2wd 6L80 needs a t-case, and a few others.

As far as the 6L80, they have a tune-able and adaptive TCM, tap shift-able, and they hold a good bit of power in stock form, 4.02:1 first, double overdrive. I'll be driving this truck on the street a good bit, so the double OD is a plus. Also the super deep 1st gear is going to be a huge advantage when it comes to getting a good crawl ratio AND keeping it fairly street-able since I won't have to have stupid low axle gearing.

Currently doing an LS swap on my 91 burb and had looked into using the 6 speed. I found a thread in my research that documents cutting some material off the output shaft and having Moser respline it for a Np241. You then just buy the GM 4wd adapter for the transmission. GM adapter #24237397. Moser quoted me $125 to cut and respline with 2 day turnaround just a few weeks ago..

The thread that I found can be viewed by typing in "6l90e to Np241c" on google. It is on another forum dedicated to a different manufacturer... I would post the link but I do not know if that is allowed here.

Only problem is that the thread is for a 90e and you have a 80e. I do not remember the exact spline counts or diameters but I wonder if the smaller shaft size of the 80e could be resplined for the common 27 spline input just like the larger 90e output being resplined for the 32 spline.

Maybe this information is beneficial to you or maybe it isn't just thought I would share some knowledge to possibly help you with the swap.

I'm patiently waiting for the Youtube videos...

 

[CTA791]

Maybe this information is beneficial to you or maybe it isn't just thought I would share some knowledge to possibly help you with the swap.

I'm patiently waiting for the Youtube videos...

Thanks for sharing. I’m sorta hung up at the moment on the t-case. Just glancing, I thought I had a factory 205. Got it pulled out and 40 years of crud cleaned off, turned out to be a 203. While a 203 is a decent case, it’s still 2:1, and will require some cash to get it converted to part time.

I would really like to have a decently deep low ratio (2.5:1 or more. 4:1 would be tits). I guess I’m part way to having a 203/205 doubler, but good lord those parts are expensive. Atlas would be giant tits, but they’re even more expensive. I “messed up” when I paid a premium for a Chevy Dana 60. It does bolt right in and has kingpin knuckles, but the passenger drop is a limiting factor when it comes to t-case options.

I think I’ve also narrowed in on a 241. People hate on the chain driven aluminum cases, but I don’t buy into all that. You pretty much only break t-cases if you’re jumping your truck, or you got 1000hp...I’m not, and I don’t. 241 is 32 spline input (sometimes), 2.72:1 low and relatively inexpensive, though they are getting harder to find as passenger drop and need an SYE.

The 6L80e 2wd tail shaft is really long, and 32 spline stock. I’m not sure why they made the 90e different with an odd-ball 29 spline tail shaft. Of course, you can buy input adapters for most popular cases. But a 32 spline input 241 will fit up to a stock 80e tail shaft once it is cut down to length.

 

[Smokinthehippies]

You don’t have to justify using a 241. They’re a great case. The biggest worry is smashing it on a rock or the chain getting slack and wearing thru the case.

So build a skid plate. And before you install it just split the case to check for excessive wear on the chain. If not boot it back up.

 

[CriticalAction]

You don’t have to justify using a 241. They’re a great case. The biggest worry is smashing it on a rock or the chain getting slack and wearing thru the case.

So build a skid plate. And before you install it just split the case to check for excessive wear on the chain. If not boot it back up.

100% agree with this. I have a 241 w/ SYE in my Blazer. It works well. The other thing I would look at is crawl ratio. You have such a low first gear it will help your situation for gearing quite a bit more. Even 2nd gear on that 6l80e is about as low as 1st on a 4l80e.

So 4.06x2.72x4.56=50.36 crawl ratio. Mine is 3.06x2.72x4.88= 40.6 crawl ratio. I felt I had all the control I needed when I was out in Moab. Others can chime in here but with an auto vehicle a 50 to 1 crawl ratio is pretty decent.

 

[Kay86K5]

@CTA791 I completely agree with the two comments above here. An SYE 241 is a fantastic option, especially for a somewhat dual purpose truck that you're building. In fact, those videos of me in Moab on the 44" boggers, that's when I had a single SYE 241 case in my rig. And my crawl ratio really wasn't that good back then (3.06 1st gear in my 700r4 and the same 4.56 axle gears as you put me at 37.95), and it still actually did alright for the couple years I wheeled it like that. You on 40's and a 50.36 crawl ratio will work really well, be plenty strong, and save you some $ for the initial build to get it up and running.

And I will second what was said above as well that as long as you build a good skid plate, and make sure front and rear drive shafts are proper lengths so they aren't bottoming out during suspension cycling, the 241 will last plenty. In my rig, 2 years ago I did end up swapping out the SYE 241 for a NWF Titan box/205 setup, but that wasn't because my SYE 241 was bad at all (in fact, that exact case is now in my oldest brothers 78 K5 with 1 tons and 37's because he wanted to get rid of his 203) it was all about getting a better overall crawl ratio for my rig on 42's. But since your tranny has such a low 1st gear, you really shouldn't have to worry about that as much. Plus, these builds area always changing. There's nothing to say that later on down the road, after this thing is running and been used, that you can't save up and swap a doubler or atlas later on. So my vote is SYE 241! Will work good for your uses for sure

 

[chris85]

Sweet start! Glad to see your back on it!

 

[CTA791]

Thanks for all the input! My thoughts exactly on everything you guys said.

I couldn’t tell you the crawl ratios in various rigs I’ve been in. I know the wife’s JKU crawl ratio is 47.65 and it’s great on the trails, sometimes a little slow. That’s why I am shooting for that 50 mark or better with the K5. Couple that with the tap shift on the 6L80, and should be pretty well rounded.

 

[85k5witha6.2]

What about an ecobox and a 205? Triple stick, 5.44:1 low. I’m into my whole doubler setup about $1000. But I’m driver drop and ford 205s are cheap.

 

[CTA791]

What about an ecobox and a 205? Triple stick, 5.44:1 low. I’m into my whole doubler setup about $1000. But I’m driver drop and ford 205s are cheap.

That's what I wanted to start with (and still do, really). I don't think you can have too much gear, but honestly, for what this rig will be, a doubler setup is probably not necessary.

Crawl ratios aside, once you get to a gearing/drivetrain/tire setup that will achieve a "crawl" speed in low/1st under half to full throttle, I don't think anything lower is really a benefit (in my opinion, of course). This desired "crawl" speed is dependent on what you want to do with your rig, specifically. But if you can use most of the throttle in low/1st and still be around a desired wheel speed, that's really all the control you need.

What I'll probably do is get the drivetrain set up with a 241, the 40" tires, and throw together a homemade rear driveshaft to see just what it feels like. I'd hate to get front and rear shafts made up and then want to change up the t-case a month later

 

[Fastereddie]

You can remove the vacuum pump and install a billet bracket for power steering pump. We just did it on a LJ jeep swap. I’ve helped do a few gen v swaps in jeeps, but getting ready to start my first into a K5 today.

 

[CTA791]

You can remove the vacuum pump and install a billet bracket for power steering pump. We just did it on a LJ jeep swap. I’ve helped do a few gen v swaps in jeeps, but getting ready to start my first into a K5 today.

Probably doing the full PSC kit on mine. I’ve read a lot about PS conversions and possibly needing to convert back to an LS style water pump...possibly needing to convert the AC compressor. Lol I have no clue though, I’ll cross that bridge when I get there.

But I’m interested in your install into the K5, shoot me a link if there’s a thread. I’d like to learn as much as I can.

 

[deadman]

Holley sells a Mid-Mount accessory kit setup that has pretty much everything you need as far as water pump. alt, a/c, p/s

 

[CTA791]

Bigger task than I anticipated...

 

[Kay86K5]

What's all that for? Blasting frame or something? Making it easier for drivetrain install?

 

[jeff in co]

Rivalry ????

 

[CTA791]

What's all that for? Blasting frame or something? Making it easier for drivetrain install?

Both. Since LT swap will require new crossmembers and mounts for everything and I have access to equipment to build them, I’m just gonna tear out all the stock stuff and redo. Frame is a tiny bit tweaked as well, I can fix that in the process. Beef up the steering box location. Basically, as much of the cutting and welding I can on it now while it’s easy, then clean it up and paint. Steam wash the underside of the body. New body bushings and hardware as well before I put the body back on.

I think it’s mildly risky, but I think I can use my measurements and mount the new drivetrain with the body off. Wouldn’t be a big deal to lift it up and test fit I guess. Putting a 1” body puck in there as well, so will have a little extra clearance.

Rivalry ????

Haha, no way! The guy that had the Blazer before I got it is a bammer Good eye though!

The wife and I both graduated from Auburn.

 

[nvrenuf]

The wife and I both graduated from Auburn.

Good to know, everyone will start typing slower. I had to.

 

[jeff in co]

Haha, no way! The guy that had the Blazer before I got it is a bammer Good eye though!

The wife and I both graduated from Auburn.

Nice. My daughter looked at Auburn but decided on Texas A&M. I thought Auburn campus was really nice though. Cool engineering lab!